motion of the staff assembly. This chart was drawn up by the Uni- 

 versity of California Fluid Mechanics Laboratory (Rauch, 19h$) from 

 a theoretical consideration of the water particle motion at the 

 depth of the damping disk and from the relative motion of the disk 

 through the water as the buoyant force on the staff changes due to 

 wave action. The "true significant height" is obtained by entering 

 the ordinate with the "apparent significant height" and the abscissa 

 with the average frequency, interpolating between the curves plotted 

 on the chart as necessary. Electrical-mechanical analyzers based 

 on the auto-correlation function are being applied to ocean wave 

 traces which show promise of more accurately describing the components 

 of wave action (Pierson, 19i>l$ Seiwell and Wadsworth, 19h9; Seiwell, 

 May 1950, Sept. 1950; and Snodgrass, 1950). Consideration is being 

 given to the application of one of these methods to the electric 

 wave staff records. 



A field calibration check was made by the University of Cali- 

 fornia in 115 feet of water using the photographic method with an 

 anchored buoy and the floating $0-Foot Damping Disk System. The 

 results from the floating system averaged 0„9 foot greater than from 

 the anchored buoy system. The wave period at the time was about 10 

 seconds, which indicates waves of sufficient length were present to 

 cause the bottom to compress the orbits of particle motion. As the 

 calibration curves do not take into account any bottom effect, it 

 would seem that the correction values introduced by the curves would 

 be too large, thus attributing more motion to the staff than actually 

 took place. This would account to some extent for the larger average 

 value obtained with the floating system. It should be recognized 

 here that using these calibration curves excludes the use of this 

 instrument in areas having a depth less than 1/2 wave length where 

 the bottom effect is present. Further field checks of this type are 

 contemplated. 



A small amount of data obtained on a recent oceanographic cruise 

 has been compared with computed values using the Sverdrup-Munk method. 

 The results were very encouraging, particularly with regard to wave 

 height. 



